A2 Hardened Platen for belt grinder

H

Heli00

Joined
Oct 19, 2017
Messages
340
Hi,

I have a KMG belt grinder and the platen does not last at all. It groves pretty fast when I profile the blades.

I suppose I could use the wheel, but I already ordered some A2 PFG bar stock and would like to confirm the HT with you.

The platen dimensions are 3/8" x 2" x 8 1/8".

Since this is thicker than a knife blade, what is the proper HT regiment?

Here is what I have for knives. I never tried it yet, just wrote it down for future reference.

Would this work for the platen?

1. Wrap in SS foil.

2. Preheat:
1450F for 10 min
Then ramp fast to austenizing temp

3. Austenitizing:
1775F for 45min
Then aluminum plate quench

Probably no Cryo is needed for the platen.

4. Temper:
Maybe first 2h at 350F, then test hardness and take it from there.

What should the final hardness of the platen be?

Thanks in advance,
Constantin
 
Platen from HSS steel don t last to me long enough to justify cutting new one ....WHY you not use ceramic glass ....they are totally other world if you ask me . Even ceramic tile work better and last longer then steel one ..in my case .
 
Natlek said:
Platen from HSS steel don t last to me long enough to justify cutting new one ....WHY you not use ceramic glass ....they are totally other world if you ask me . Even ceramic tile work better and last longer then steel one ..in my case .
Click to expand...

Thanks Natlek, good point.

I understand there is a static electricity issue with the ceramic glass platen cover that I didn’t wanted to put up with, that’s why I wanted to stay with steel.

Plus one may radius the edges of the platen to their likings. I suppose the same could be true with a glass platen, but the static issue is what primarily concerns me.

The KMG platen is unhardened steel, so a hardened platen I thought should last a lot longer.

Cheers,
Constantin
 
I recently put a ceramic glass liner on my platen. I have had zero of static electricity issues.
 
This is how I do it. :thumbsup:

I use pretty thick O1 (15mm or 0.6") for my bevel grinding flat platen (doesn't get as hot). When hardening, I don't temper, just use it at AS-quench hardness around 66 HRC. Once a month I run it through my SGA and it's dead flat again, takes about 5 minutes.

I've found that what caused most of the wear on my flat platen was the profiling of blades using heavy pressure, low grit belts and high SFPM. So to avoid this I have two flat platen attachments, one with a mild steel platen for profiling and the other one with the hardened O1. The mild steel one for profiling doesn't have to be totally flat, it will wear out over time and I'll just replace it without much effort.
 
Stromberg Knives said:
This is how I do it. :thumbsup:

I use pretty thick O1 (15mm or 0.6") for my bevel grinding flat platen (doesn't get as hot). When hardening, I don't temper, just use it at AS-quench hardness around 66 HRC. Once a month I run it through my SGA and it's dead flat again, takes about 5 minutes.

I've found that what caused most of the wear on my flat platen was the profiling of blades using heavy pressure, low grit belts and high SFPM. So to avoid this I have two flat platen attachments, one with a mild steel platen for profiling and the other one with the hardened O1. The mild steel one for profiling doesn't have to be totally flat, it will wear out over time and I'll just replace it without much effort.
Click to expand...

OK thanks.

Same here profiling just kills the mild steel platen.

Is the SGA a surface grind attachment for the belt grinder? Which one do you have?
 
Heli00 said:
OK thanks.

Same here profiling just kills the mild steel platen.

Is the SGA a surface grind attachment for the belt grinder? Which one do you have?
Click to expand...

I would hazard a guess that any kind of platen will eventually break down, my recommendation would still be to separate the rough use profiling platen from the good stuff used for fine bevel grinding. ;)

And yes, it's a surface grinder attachment. And I made it myself. It's based on the designs you'll find in the thread here.

HE3NDiD.jpg
 
Stromberg Knives said:
I would hazard a guess that any kind of platen will eventually break down, my recommendation would still be to separate the rough use profiling platen from the good stuff used for fine bevel grinding. ;)

And yes, it's a surface grinder attachment. And I made it myself. It's based on the designs you'll find in the thread here.

HE3NDiD.jpg
Click to expand...
Oh, I totally agree. I’ll have separate platens for profiling and bevel work.

Thanks for the sga reference, I’ll have a look.

Thanks again,
Constantin
 
The unhardened kmg platen ( :confused: ) didnt hold up at all but the platen I got from Nathan has held up amazingly even though I treat it like a stepchild at times.
 
Spalted said:
The unhardened kmg platen ( :confused: ) didnt hold up at all but the platen I got from Nathan has held up amazingly even though I treat it like a stepchild at times.
Click to expand...
Yeah, I tried to get one about a year ago, but was too late, sold out. So I decided to make my own now and be self sufficient.
 
Just an update, I’m getting 4 platens out of the bar stock I bought, at a cost of about $30 or so each, not bad at all, very satisfied.
 
HT Update, just in case others are interested.

65 HRC “as quenched” NO Cryo, very satisfied with this results.

In this platen case, I’m going to skip cryo and tempering. I don’t think would matter much, let me know if you think otherwise.

Ended up going with 60 min at 1775 F, for the 3/8” x 2” x 8” plate.

Quenched between aluminum plates + some compressor air while there. Then cold water for one minute. Doubt the cold water done anything, but I just did it anyway.

Cheers,
Constantin
 
why NOT profile on a wheel? The wheel is much more aggressive in my experience, and the abrasive lasts longer. Then square things up on the platen.
 
daizee said:
why NOT profile on a wheel? The wheel is much more aggressive in my experience, and the abrasive lasts longer. Then square things up on the platen.
Click to expand...
This is good advice. :thumbsup:

You can profile very aggressively with a wheel, and without any discernible wear on the wheel. This is how I used to do it. Rough profiling on the wheel and then squaring up on the flat platen.

Nowadays I cut my profiles very tight on the bandsaw and go directly to the flat platen for the final profiling. And most of the time I even run it horizontally with a work rest.
 
I cut it rough on the bandsaw then freehand on 10" wheel and finally with horizontal platen and work rest to square up.
 
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